KR20010113322A - Method of manufacturing a capacitor in a semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a capacitor of a semiconductor device, wherein A _1-x Re _x B _z O ₃ (A = Y, La; Re = Sr, Ca; B = Cr, having high electrical conductivity and low oxygen diffusion coefficient) Mn, Fe; 0 ≦ _x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9 ≦ Z ≦ 1.1) and La _1-x Sr _x Co _1-y Cr _y O _{3 with} perovskite oxide The semiconductor device can improve the reliability of the device by minimizing lattice mismatch by using as the bottom electrode and the top electrode of the BST capacitor to improve the crystallinity of the BST and preventing the diffusion prevention film of the contact hole from being oxidized during the subsequent high temperature thermal process. A method of manufacturing a capacitor is provided.

Description

Method of manufacturing a capacitor in a semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a capacitor of a semiconductor device. In particular, a perovskite oxide having a high electrical conductivity and a low diffusion coefficient of oxygen is used as a lower electrode and an upper electrode of a BST capacitor, thereby minimizing lattice mismatch. The present invention relates to a method for manufacturing a capacitor of a semiconductor device capable of improving the crystallinity of the device and preventing the diffusion prevention film of the contact hole from oxidizing during the subsequent high temperature thermal process.

Until now, precious metals or precious metal oxides such as Pt, lr, lrO ₂ , Ru, and RuO ₂ have been used as electrode materials for BST capacitors for DRAM. However, these precious metals have very good oxygen adsorption and high oxygen solubility. In addition, since oxygen atoms diffuse rapidly along the grain boundaries, when contacted with BST, oxygen of the BST is moved toward the nitride diffusion barrier below the lower electrode to oxidize the nitride diffusion barrier during high temperature heat treatment. In particular, when the metal itself, such as Pt, lr, or Ru, is used as an electrode, the dielectric constant decreases as the thickness of the BST becomes thinner. Therefore, there is a limit to thinning the thickness of the BST to increase the degree of integration. Moreover, when BST is deposited on these noble metals and noble metal oxides, the BST does not crystallize properly at the interface due to lattice mismatch and thus exists as an amorphous layer, thereby reducing the effective dielectric constant. Perovskite (Perovskite) oxide to improve the electrode properties of this noble metal having a lattice structure, such as BST, for example, there has been an attempt to use such as SrRuO _3, BaRuO ₃ as an electrode. However, these oxides have a disadvantage in that they have a high oxygen diffusion coefficient because they have high electrical conductivity but still use Ru. For this reason, when TiN is used as the diffusion barrier, there is a disadvantage that TiN is oxidized to TiO ₂ even after heat treatment at 550 ° C.

Accordingly, the present invention provides a method of manufacturing a capacitor of a semiconductor device capable of solving the above problems by forming a BST capacitor electrode using a perovskite oxide having a high electrical conductivity, a low oxygen diffusion coefficient, and a low oxygen vacancies defect concentration. Its purpose is to.

The present invention for achieving the above object is to form a contact hole for exposing a predetermined region of the semiconductor substrate by etching a predetermined region of the first insulating film after forming a first insulating film on the semiconductor substrate having a predetermined structure formed And filling the contact hole by laminating a polysilicon layer, an ohmic contact layer, and a diffusion barrier layer, forming a second insulating layer on the entire structure, and then exposing a predetermined region of the diffusion barrier layer and the first insulating layer. Etching and A _1-x Re _x B _z O ₃ (A = Y, La; Re = Sr, Ca; B = Cr, Mn, Fe; 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9 ≦ Z ≦ 1.1) and La _1-x Sr _x Co _1-y Cr _y O ₃ to form a lower electrode, a BST film is formed over the entire structure, and A _1-x Re _x B _z O ₃ (A = Y, La; Re = Sr, Ca; B = Cr, Mn, Fe; 0 ≦ _x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9 ≦ Z ≦ 1.1) and La _1-x Sr _x Co Top with any of _1-y Cr _y O ₃ It characterized in that it comprises a step of forming an electrode.

1 is a graph comparing the electrical conductivity of La _0.75 Sr _0.35 CrO ₃ and La _0.7 Ca _0.3 CrO ₃ .

Figure 2 is a graph comparing the oxygen vacancies diffusion coefficient of La _0.73 Ca _0.27 Cr _0.98 O ₃ and La _0.9 Sr _0.1 CoO ₃ .

3 (a) to 3 (e) are cross-sectional views of devices sequentially shown to explain a method of manufacturing a capacitor of a semiconductor device according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

11 semiconductor substrate 12 oxide film

13: nitride film 14: polysilicon film

15: ohmic contact layer 16: diffusion barrier

17 insulating film 18 first perovskite oxide

19: BST dielectric film 20: second perovskite oxide

The present invention provides La _1-x Ca _x CrO ₃ (LCC), La _1-x Sr _x CrO ₃ (LSC), Y _1-x as an electrode material when fabricating a BST dielectric film capacitor of a DRAM device having an integrated density of 1 Gbit or more. Oxides with perovskite structures such as Ca _x CrO ₃ (YCC), Y _1-x Sr _x CrO ₃ (YSC), and La _1-x Sr _x Co _1-y Cr _y O ₃ (LSCC) Provides a method of using conductors. When the oxide conductor is used, the lattice mismatch is minimized when the BST dielectric film is deposited on the oxide electrode, thereby increasing the crystallinity and the dielectric constant loss at the interface because the interface between the two oxides having similar interfaces between the electrode and the BST dielectric film is similar. There is almost no. When Pt is used as an electrode, the dielectric constant decreases as the thickness of the BST film becomes thin. In the case of the oxide electrode, since there is no such phenomenon, a high dielectric constant can be obtained even by applying a thin BST dielectric film. have.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a graph comparing the electrical conductivity of La _0.75 Sr _0.35 CrO ₃ and La _0.7 Ca _0.3 CrO ₃ . As shown, the electrical conductivity at room temperature is 12Ω ^-1 cm ^-1 and 6Ω ^-1 cm ^-1, respectively. Since the large electrode area is required to increase the dielectric constant of the capacitor, the above value is sufficient for the application to the actual electrode.

2 is a graph comparing the oxygen vacancies diffusion coefficients of La _0.73 Ca _0.27 Cr _0.98 O ₃ and La _0.9 Sr _0.1 CoO ₃ . As described above, it can be seen that the oxygen vacancies diffusion coefficient of the LCC is about 10 times smaller than that of LSCO. Therefore, it can be predicted that when LCC is used as the lower electrode of the capacitor, much less oxygen is transmitted to the nitride diffusion barrier than LSCO. In addition, when the perovskite oxide is used as an electrode, the crystallinity of the BST dielectric film is better than that of using a noble metal electrode such as Pt, which not only lowers the heat treatment temperature for crystallization of BST but also increases the dielectric constant, thereby increasing the reliability of the capacitor. do.

3 (a) to 3 (g) are cross-sectional views of devices sequentially shown to explain a method of manufacturing a capacitor of a semiconductor device according to an embodiment of the present invention.

Referring to FIG. 3A, an oxide film 12 is formed on a semiconductor substrate 11 on which a predetermined structure for manufacturing a semiconductor device is formed, and an nitride film having an excellent etching selectivity with respect to the oxide film 12 thereon ( 13). Predetermined regions of the nitride film 13 and the oxide film 12 are etched to form a first contact hole exposing a predetermined region of the semiconductor substrate 11.

Referring to FIG. 3B, a polysilicon film 14 having a thickness of 700 to 3000 Å is formed on the entire structure by CVD to fill the first contact hole. The entire over-etching process is performed so that the polysilicon film 14 formed on the nitride film 13 is completely removed and a part of the polysilicon film 14 embedded in the first contact hole is removed. The polysilicon film 14 removed from the first contact hole is removed to a depth of 200-1500 로부터 from the top of the first contact hole.

Referring to FIG. 3C, a Ti film or a Co film is formed on the entire structure including the first contact hole. The heat treatment process is performed to form a titanium silicide layer or a cobalt silicide layer as the ohmic contact layer 15 on the polysilicon layer 14 in the first contact hole. At this time, the ohmic contact layer 15 is formed to a thickness of 100 to 500 kPa, and the Ti film or Co film remaining on the nitride film 13 is removed. A TiN film or a TiAlN film is formed as a diffusion barrier film 16 on the entire structure including the first contact hole by the PVD method or the CVD method. At this time, the diffusion barrier 16 is formed to a thickness of 700 to 3000 kPa. The CMP process is performed to remove and planarize the diffusion barrier layer 16 formed on the nitride layer 13.

Referring to FIG. 3 (d), after forming the insulating layer 17 over the entire structure, the second contact hole is formed to expose the lower diffusion barrier layer 16. The insulating film 17 is formed of, for example, a USG film or a PSG film with a thickness of 2000 to 15000 GPa. In addition, the second contact hole formed by etching the insulating layer 17 is formed wider than the width of the first contact hole. The first perovskite oxide 18 is formed on the entire structure by the PVD method or the CVD method, and a rapid thermal process (RTP) is performed to stabilize the oxide electrode. The first perovskite oxide 18 is A _1-x Re _x B _z O ₃ having the composition 0 ≦ _x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9 ≦ Z ≦ 1.1 (A = Y, La; Re = Sr, Ca; B = Cr, Mn, Fe) and La _1-x Sr _x Co _1-y Cr _y O ₃ , and the thickness thereof is formed to a thickness of 150 to 500 kPa on the sidewall of the second contact hole. do. In addition, the rapid heat treatment step is carried out for 5 to 180 seconds in the temperature range of 500 to 750 ℃ using a mixed gas of oxygen and nitrogen or oxygen and argon. The entire surface is etched or a CMP process is performed to remove the first perovskite oxide 18 on the insulating layer 17 to form a lower electrode.

Referring to FIG. 3 (e), the BST film 19 is formed to a thickness of 150 to 500 GPa over the entire structure by CVD, followed by rapid heat treatment to crystallize. The rapid heat treatment process for crystallizing the BST film 19 is performed for 5 to 180 seconds at a temperature of 500 to 750 ° C using a mixed gas of oxygen and nitrogen or oxygen and argon. Then, the second perovskite oxide 20 is formed by the upper electrode by the PVD method or the CVD method to complete the manufacture of the capacitor. The second perovskite oxide 20 is formed in the same manner as the first perovskite oxide 18, and the thickness thereof is about 150 to 500 kPa based on the side surface. In order to stabilize the characteristics of the capacitor, a heat treatment process is performed for 1 to 30 minutes at a temperature of 500 to 800 ° C. using a mixed gas of oxygen and nitrogen or oxygen and argon.

As described above, when the BST capacitor is manufactured using a perovskite oxide electrode having a low oxygen vacancies diffusion coefficient, the BST dielectric layer has excellent crystallinity while preventing oxidation of the diffusion barrier layer, thereby having a high dielectric constant and a low leakage current. Capacitors of quality can be manufactured.

Claims (14)

Forming a contact hole exposing a predetermined region of the semiconductor substrate by etching a predetermined region of the first insulating layer after forming a first insulating layer on the semiconductor substrate having a predetermined structure; Depositing the contact hole by laminating a polysilicon layer, an ohmic contact layer, and a diffusion barrier layer; Forming a second insulating film on the entire structure and etching the exposed portions of the diffusion barrier film and the first insulating film; A _1-x Re _x B _z O ₃ (A = Y, La; Re = Sr, Ca; B = Cr, Mn, Fe; 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9 ≦ Z ≤1.1) and forming a lower electrode with any one of La _1-x Sr _x Co _1-y Cr _y O ₃ , A BST film is formed over the entire structure, and A _1-x Re _x B _z O ₃ (A = Y, La; Re = Sr, Ca; B = Cr, Mn, Fe; 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.9≤Z≤1.1) and La _1-x Sr _x Co _1-y Cr _y O _{3 The} method of manufacturing a capacitor of a semiconductor device comprising the step of forming an upper electrode. The method of claim 1, wherein the polysilicon film is formed to a depth of 200 to 1500 로부터 from an upper portion of the contact hole. The capacitor of claim 1, wherein the ohmic contact layer is a titanium silicide layer or a cobalt silicide layer formed by a reaction with the polysilicon layer by forming a Ti layer or a Co layer and performing a heat treatment process. Way. 2. The method of claim 1, wherein the ohmic contact layer is formed to a thickness of 100 to 500 GPa. The method of claim 1, wherein the diffusion barrier is formed of a TiN film or a TiAlN film. The method of claim 1, wherein the lower electrode is formed to have a thickness of about 150 to about 500 μm on an etched sidewall of the second insulating layer. The method of claim 1, further comprising performing a rapid heat treatment process after forming the lower electrode. The method of claim 7, wherein the rapid heat treatment process is performed at a temperature of 500 to 750 ° C. for 5 to 180 seconds using oxygen and nitrogen or a mixed gas of oxygen and argon. The method of claim 1, wherein the BST film is formed to a thickness of 150 to 500 GPa. The method of claim 1, further comprising: performing a rapid heat treatment process after forming the BST film. The method of claim 10, wherein the rapid heat treatment is performed at a temperature of 500 to 750 ° C. for 5 to 180 seconds using oxygen and nitrogen or a mixed gas of oxygen and argon. 2. The method of claim 1, wherein the upper electrode is formed to a thickness of 150 to 500 kHz from a sidewall of the BST film. The method of claim 1, further comprising performing a heat treatment process after forming the upper electrode. The method of claim 13, wherein the heat treatment is performed at a temperature of 500 to 800 ° C. for 1 to 30 minutes using oxygen and nitrogen or a mixed gas of oxygen and argon.